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Improved Registration of 3D CT Angiography with X-ray Fluoroscopy for Image Fusion During Transcatheter Aortic Valve Implantation

The fusion of 3D anatomical models derived from high-fidelity pre-interventional computed tomography angiography (CTA), and x-ray (XR) fluoroscopy to ...

Ulm University Medical Center

DELIVER (DELiverability of the Resolute Integrity Stent in All-Comer Vessels and Cross-OvER stenting) was a prospective, multicenter, all-comers registry to assess the deliverability of the Resolute Integrity™ zotarolimus-eluting stent (R-ZES).

Deliverability of the Resolute Integrity stent and a post hoc comparison of radial and femoral access: the DELIVER study.

Myofibrillar myopathies (MFM) are progressive diseases of human heart and skeletal muscle with a severe impact on life quality and expectancy of affected patients. Although recently several disease genes for myofibrillar myopathies could be identified, today most genetic causes and particularly the associated mechanisms and signaling events that lead from the mutation to the disease phenotype are still mostly unknown. To assess whether the zebrafish is a suitable model system to validate MFM candidate genes using targeted antisense-mediated knock-down strategies, we here specifically inactivated known human MFM disease genes and evaluated the resulting muscular and cardiac phenotypes functionally and structurally. Consistently, targeted ablation of MFM genes in zebrafish led to compromised skeletal muscle function mostly due to myofibrillar degeneration as well as severe heart failure. Similar to what was shown in MFM patients, MFM gene-deficient zebrafish showed pronounced gene-specific phenotypic and structural differences. In summary, our results indicate that the zebrafish is a suitable model to functionally and structurally evaluate novel MFM disease genes in vivo. 

In vivo characterization of human myofibrillar myopathy genes in zebrafish.

Alternative splicing is one of the major mechanisms through which the proteomic and functional diversity of eukaryotes is achieved. However, the complex nature of the splicing machinery, its associated splicing regulators and the functional implications of alternatively spliced transcripts are only poorly understood. Here, we investigated the functional role of the splicing regulator rbfox1 in vivo using the zebrafish as a model system. We found that loss of rbfox1 led to progressive cardiac contractile dysfunction and heart failure. By using deep-transcriptome sequencing and quantitative real-time PCR, we show that depletion of rbfox1 in zebrafish results in an altered isoform expression of several crucial target genes, such as actn3a and hug. This study underlines that tightly regulated splicing is necessary for unconstrained cardiac function and renders the splicing regulator rbfox1 an interesting target for investigation in human heart failure and cardiomyopathy. 

RNA splicing regulated by RBFOX1 is essential for cardiac function in zebrafish.

Orchestrated protein synthesis and degradation is fundamental for proper cell function. In muscle, impairment of proteostasis often leads to severe cellular defects finally interfering with contractile function. Here, we analyze for the first time the role of Atrogin-1, a muscle-specific E3 ubiquitin ligase known to be involved in the regulation of protein degradation via the ubiquitin proteasome and the autophagy/lysosome systems, in the in vivo model system zebrafish (Danio rerio). We found that targeted inactivation of zebrafish Atrogin-1 leads to progressive impairment of heart and skeletal muscle function and disruption of muscle structure without affecting early cardiogenesis and skeletal muscle development. Autophagy is severely impaired in Atrogin-1-deficient zebrafish embryos resulting in the disturbance of the cytoarchitecture of cardiomyocytes and skeletal muscle cells. These observations are consistent with molecular and ultrastructural findings in an Atrogin-1 knockout mouse and demonstrate that the zebrafish is a suitable vertebrate model to study the molecular mechanisms of Atrogin-1-mediated autophagic muscle pathologies and to screen for novel therapeutically active substances in high-throughput in vivo small compound screens (SCS). 

Atrogin-1 Deficiency Leads to Myopathy and Heart Failure in Zebrafish.

In search for novel key regulators of cardiac valve formation, we isolated the zebrafish cardiac valve mutant ping pong (png). We find that an insertional promoter mutation within the zebrafish mediator complex subunit 10 (med10) gene is leading to impaired heart valve formation. Expression of the T-box transcription factor 2b (Tbx2b), known to be essential in cardiac valve development, is severely reduced in png mutant hearts. We demonstrate here that transient reconstitution of Tbx2b expression rescues AV canal development in png mutant zebrafish. By contrast, overexpression of Forkhead box N4 (Foxn4), a known upstream regulator of Tbx2b, is not capable to reconstitute tbx2b expression and heart valve formation in Med10-deficient png mutant hearts. Interestingly, hyaluronan synthase 2 (has2), a known downstream target of Tbx2 and producer of hyaluronan (HA) - a major ECM component of the cardiac jelly and critical for proper heart valve development - is completely absent in ping pong mutant hearts. We propose here a rather unique role of Med10 in orchestrating cardiac valve formation by mediating Foxn4 dependent tbx2b transcription, expression of Has2 and subsequently proper development of the cardiac jelly.

The mediator complex subunit Med10 regulates heart valve formation in zebrafish by controlling Tbx2b-mediated Has2 expression and cardiac jelly formation.

Pulmonary vein isolation (PVI) with the cryoballoon is an established treatment for symptomatic atrial fibrillation. The second-generation cryoballoon increased efficacy in comparison to the first-generation cryoballoon. The third-generation cryoballoon was designed with a shorter distal tip to facilitate real-time recording of pulmonary vein (PV) isolation. Here, we compared the rate of real-time recordings of PVI of the second- and third-generation cryoballoon.

Increased rate of observed real-time pulmonary vein isolation with third-generation short-tip cryoballoon.

Pulmonary vein isolation is an established therapy for symptomatic atrial fibrillation. Despite the fact that incidence and prevalence of atrial fibrillation increases with age, patients over 75 years of age have been excluded in all major atrial fibrillation ablation trials. Pulmonary vein isolation with the cryoballoon has been shown to be equally effective compared to irrigated radiofrequency catheter ablation, but patients over 75 years have also been excluded. The 2nd generation cryoballoon has shown superior efficacy compared to the 1st generation cryoballoon. The aim of the study was to assess the efficacy of pulmonary vein isolation with the 2nd generation cryoballoon for symptomatic atrial fibrillation in elderly patients over 75 years.

Clinical outcome of 2nd generation cryoballoon pulmonary vein isolation in patients over 75 years of age.

The optimal freeze duration in cryoballoon pulmonary vein isolation (PVI) is unknown. The 3rd generation cryoballoon facilitates observation of the time-to-isolation (TTI) and thereby enables individualized cryoenergy titration. To evaluate the efficacy of an individualized freeze duration we compared the clinical outcome of patients treated with a TTI-guided ablation protocol to the outcome of patients treated with a fixed ablation protocol.

Time-to-isolation guided titration of freeze duration in 3rd generation short-tip cryoballoon pulmonary vein isolation - Comparable clinical outcome and shorter procedure duration.

Missense mutations in the four and a half LIM domain 1 (FHL1) gene were found to cause X-linked inherited myopathies of both skeletal and heart muscles. However, the mechanisms by which FHL1 mutations impact on FHL1 function and lead to alteration of muscle structure and function have not been deciphered yet. We generated here by Morpholino-modified antisense oligonucleotide-mediated gene knockdown fHL1-deficient zebrafish embryos. Similar to the human situation, fhl1a-morphants zebrafish displayed severe skeletal and heart muscle myopathy. Whereas ectopic expression of wild-type FHL1 (FHL1 wt) suppressed both skeletal and heart muscle myopathy in fhl1a-morphants zebrafish, overexpression of the FHL1-opathy associated human mutations FHL1-H123Y, FHL1-C132F or FHL1-C224W did not rescue skeletal and heart muscle myopathy in fhl1a-morphants. Overexpression of FHL1-H123Y, FHL1-C132F or FHL1-C224W in wild-type zebrafish did not induce myopathy in a dominant-negative mode. Altogether these results indicate that FHL1 mutations found to cause X-linked FHL1-opathies in humans consistently lead to severely impaired FHL1 function.

A zebrafish model for FHL1-opathy reveals loss-of-function effects of human FHL1 mutations.

The genetic underpinnings that orchestrate the vertebrate heart rate are not fully understood yet, but of high clinical importance, since diseases of cardiac impulse formation and propagation are common and severe human arrhythmias. To identify novel regulators of the vertebrate heart rate, we deciphered the pathogenesis of the bradycardia in the homozygous zebrafish mutant hiphop (hip) and identified a missense-mutation (N851K) in Na/K-ATPase α1-subunit (atp1a1a.1). N851K affects zebrafish Na/K-ATPase ion transport capacity, as revealed by in vitro pump current measurements. Inhibition of the Na/K-ATPase in vivo indicates that hip rather acts as a hypomorph than being a null allele. Consequently, reduced Na/K-ATPase function leads to prolonged QT interval and refractoriness in the hip mutant heart, as shown by electrocardiogram and in vivo electrical stimulation experiments. We here demonstrate for the first time that Na/K-ATPase plays an essential role in heart rate regulation by prolonging myocardial repolarization.

Article	Year
Deliverability of the Resolute Integrity stent and a post hoc comparison of radial and femoral access: the DELIVER study. Cardiovascular revascularization medicine : including molecular interventions\| PubMed ID: 25178669	2014
In vivo characterization of human myofibrillar myopathy genes in zebrafish. Biochemical and biophysical research communications\| PubMed ID: 25866181	2015
RNA splicing regulated by RBFOX1 is essential for cardiac function in zebrafish. Journal of cell science\| PubMed ID: 26116573	2015
Atrogin-1 Deficiency Leads to Myopathy and Heart Failure in Zebrafish. International journal of molecular sciences\| PubMed ID: 26840306	2016
The mediator complex subunit Med10 regulates heart valve formation in zebrafish by controlling Tbx2b-mediated Has2 expression and cardiac jelly formation. Biochemical and biophysical research communications\| PubMed ID: 27343557	2016
Increased rate of observed real-time pulmonary vein isolation with third-generation short-tip cryoballoon. Journal of interventional cardiac electrophysiology : an international journal of arrhythmias and pacing\| PubMed ID: 27448816	2016
Clinical outcome of 2nd generation cryoballoon pulmonary vein isolation in patients over 75 years of age. Journal of cardiology\| PubMed ID: 27650097	2017
Time-to-isolation guided titration of freeze duration in 3rd generation short-tip cryoballoon pulmonary vein isolation - Comparable clinical outcome and shorter procedure duration. International journal of cardiology\| PubMed ID: 29425568	2018
A zebrafish model for FHL1-opathy reveals loss-of-function effects of human FHL1 mutations. Neuromuscular disorders : NMD\| PubMed ID: 29735270	2018
Mutation of the Na/K-ATPase Atp1a1a.1 causes QT interval prolongation and bradycardia in zebrafish. Journal of molecular and cellular cardiology\| PubMed ID: 29750993	2018

Wolfgang Rottbauer

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